PROTECTION OF THE PUBLIC UNDER ACCIDENT CONDITIONS

The possible consequences of design basis accidents and severe accidents should be determined to demonstrate compliance with design targets. 

Compliance with design targets for design basis accidents should be assessed by means of safety analyses [10]. In cases where the safety analysis shows that the acceptance criteria are not met, additional protective features should be incorporated into the design or operational measures should be developed to meet the acceptance criteria. 

Generally, the releases that are evaluated for accident conditions are releases to the atmosphere, since an accidental release of radioactive substances to the aquatic environment is usually unlikely. However, this should be verified for each design or each plant, and consideration should be given, for instance, to the contamination of groundwater by leakage from the spent fuel pool, for example. 

In demonstrating compliance with the design targets for doses to the public, conservative assumptions should be made with regard to the duration of the exposure, the weather conditions, and shielding of and occupancy by the public at the time of the accident. 

For severe accident scenarios, specific analysis should be performed to demonstrate compliance with national regulatory requirements concerning both the short term and the long term consequences of an accident. The source term is usually evaluated by using best estimate methods, in contrast to the conservative assumptions that are made for design basis accidents. In addition, a probabilistic dispersion code may be used to evaluate the risk to the critical groups. 

---